Effective Date

01/17/2018

5-1.43 Monitoring requirements for water quality parameters.

All systems serving over 50,000 persons and systems that exceed the lead or copper action level shall monitor water quality parameters in addition to lead and copper in tap water in accordance with this section.

(a) Sample requirements.

(1) Sample collection method.

(i) Distribution system (tap) samples shall be representative of water quality throughout the distribution system, taking into account the number of persons served, the different sources of water, the different treatment methods employed by the system, and seasonal variability. Distribution system sampling under this section is not required to be conducted at taps targeted for lead and copper sampling under section 5-1.42(a).

(ii) Entry point samples to the distribution system shall be from locations representative of each source after treatment. If a system draws water from more than one source and the sources are combined before distribution, the system shall sample at entry point(s) representative of normal operating conditions.

(2) Number of samples.

(i) A water system conducting standard monitoring shall collect two samples for applicable water quality parameters during each monitoring period specified in subdivision (b) of this section from the number of distribution system sampling sites listed in the table below under “Standard Monitoring.” A water system conducting reduced monitoring shall collect two samples for applicable water quality parameters during each monitoring period specified in subdivision (c) of this section from the number of distribution system sampling sites listed in the table below under “Reduced Monitoring.” Such reduced monitoring sites shall be representative of the sites required for standard monitoring.

Population Served

Standard Monitoring

Reduced Monitoring

(Sample Sites)

(Sample Sites)

>100,000

25

10

10,001 to 100,000

10

7

3,301 to 10,000

3

3

501 to 3,300

2

2

101 to 500

1

1

<101

1

1

(ii) A water system conducting monitoring in accordance with subdivision (b)(1) of this section shall collect two entry point samples for each applicable water quality parameter at each entry point to the distribution system during each six-month monitoring period. A water system conducting monitoring in accordance with subdivisions (b)(2), (b)(3), and (c) of this section shall collect one entry point sample for each applicable water quality parameter at each entry point to the distribution system, or each applicable entry point in accordance with subdivision (b)(2)(iii), at the frequency specified in subdivision (b)(2)(ii).

(b) Standard Monitoring. Required samples shall be collected during six-month monitoring periods, beginning January 1 or July 1 of each calendar year.

(1) Initial sampling. All systems serving more than 50,000 persons shall measure the applicable water quality parameters during each six-month monitoring period specified in section 5-1.42(b)(1). All systems serving 50,000 or fewer persons shall measure the applicable water quality parameters during each six-month monitoring period during which the system exceeds the lead or copper action level. Applicable water quality parameters at taps and entry points include: pH; alkalinity; conductivity; water temperature; calcium; and orthophosphate or silica, as appropriate to the corrosion control treatment used.

(2) Monitoring after installation of corrosion control. Any system which installs optimal corrosion control treatment shall measure the water quality parameters at the locations and frequencies specified below during each six-month monitoring period specified in section 5-1.42(b)(2).

(i) two samples shall be collected at taps in the distribution system for the following parameters: pH; alkalinity; calcium; and orthophosphate or silica, as appropriate to the corrosion control treatment used.

(ii) one sample shall be collected at each entry point: Except as provided in subdivision (b)(2)(iii) of this section, at least one sample no less frequently than every two weeks (biweekly) for pH; alkalinity (and a reading of the dosage rate of the chemical used to adjust alkalinity, when alkalinity is adjusted); calcium; orthophosphate or silica, as appropriate to the corrosion control treatment used; and a reading of the dosage rate of the corrosion control treatment chemical used.

(iii) A ground water system may limit entry point sampling described in subdivision (b)(2)(ii) of this section to those entry points that are representative of water quality and treatment conditions throughout the system. If water from untreated ground water sources mixes with water from treated ground water sources, the system shall monitor for water quality parameters both at representative entry points receiving treatment and representative entry points receiving no treatment. Prior to the start of any monitoring under this paragraph, the system shall provide to the State written information identifying the selected entry points and documentation, including information on seasonal variability, sufficient to demonstrate that the sites are representative of water quality and treatment conditions throughout the system.

(3) Monitoring after State specifies water quality parameter values for optimal corrosion control. After the State specifies the values for applicable water quality control parameters reflecting optimal corrosion control treatment, all systems serving more than 50,000 persons and any system serving 50,000 or fewer persons that has optimal corrosion control treatment installed shall measure the applicable water quality parameters during each six-month monitoring period specified in section 5-1.42(b)(3), in accordance with subdivisions (b)(2)(i)-(iii) of this section, and determine compliance with the requirements of section 5-1.41(g) during each six-month monitoring period specified in section 5-1.42(b)(3).

(c) Reduced monitoring.

(1) Reducing the number of sampling sites. Any water system that maintains the range of State specified values for the water quality parameters reflecting optimal corrosion control treatment during each of two consecutive six-month monitoring periods under subdivision (b)(3) of this section shall continue monitoring at the entry point(s) to the distribution system as specified in subdivision (b)(2)(ii)-(iii) of this section. Such system may collect two distribution system samples for applicable water quality parameters from the reduced number of sites in accordance with subdivision (a)(2)(i) of this section during each six-month monitoring period.

(2) Reducing sampling frequency.

(i) Any water system that maintains the range of State-specified values for the water quality parameters reflecting optimal corrosion control treatment during three consecutive years of monitoring in accordance with subdivision (c)(1) of this section may reduce the frequency with which it collects the number of distribution system samples for applicable water quality parameters specified in subdivision (c)(1) of this section from every six months to annually. This sampling shall begin during the calendar year immediately following the end of the monitoring period in which the third consecutive year of six-month monitoring occurs. Any water system that maintains the range of State-specified values for the water quality parameters reflecting optimal corrosion control treatment during three consecutive years of annual monitoring under this paragraph may reduce the frequency with which it collects the number of distribution system samples for applicable water quality parameters specified in subdivision (c)(1) of this section from annually to every three years.

(ii) A water system may reduce the frequency with which it collects the number of distribution system samples for applicable water quality parameters specified in subdivision (c)(1) of this section to every three years if it demonstrates during two consecutive monitoring periods that its tap water lead level at the 90th percentile is less than or equal to the PQL for lead specified in section 5-1.40(b)(1), that its tap water copper level at the 90th percentile is less than or equal to 0.65 mg/L for copper, and that it also has maintained the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the State under section 5-1.41(f).

(iii) Monitoring conducted every three years shall be done no later than every third calendar year.

(3) A water system that conducts reduced sampling frequency shall collect these samples evenly throughout monitoring period in which samples are taken so as to reflect seasonal variability.

(4) Any water system subject to the reduced monitoring frequency that fails to operate at or above the minimum value or within the range of values for the water quality parameters specified by the State under section 5-1.41(f) for more than nine days in any six-month period shall resume distribution system tap water sampling in accordance with the number and frequency requirements in subdivision (b)(3) of this section. The water system may resume annual monitoring for water quality parameters at the tap at the reduced number of sites specified in subdivision (a)(2)(i) of this section after it has completed two subsequent consecutive six-month rounds of monitoring that meet the criteria of that subdivision and/or may resume triennial monitoring for water quality parameters at taps in the distribution system at the reduced number of sites after it demonstrates through subsequent rounds of monitoring that it meets the criteria of either subdivision (c)(2)(i) or (c)(2)(ii) of this section.

(d) Additional monitoring by systems. The results of any monitoring conducted in addition to the minimum requirements of this section shall be considered by the system and the State in making any compliance determinations (i.e., determining concentrations of water quality parameters).